Patients of all ages who are undergoing orthodontic therapy may also be missing teeth. When such is the case, a constricted maxillary arch with a lingually positioned left lateral incisor can be treated with a removable lateral expansion appliance while temporarily replacing two missing centrals. As the appliance is developed laterally, you may find it necessary to periodically build up the mesial of the centrals with composite in order to maintain superior esthetics. This allows the patient to maintain function and esthetics throughout treatment.